The present invention is generally directed to radar system timing and control, and more particularly, a radar system for concurrent operation of multiple radar functions.
Conventional radar systems frequently utilize waveforms consisting of a series of pulses. For example, a pulse radar system known to those skilled in the art might transmit a pulse train having a certain pulse repetition frequency (PRF) toward a target, receiving reflections of those pulses from the target as echoes between the transmitted pulses. Various radar systems known to those skilled in the art are used for moving target indication (MTI), synthetic aperture radar (SAR), target tracking, automatic target recognition (ATR), and dismount detection, to name but a few.
In various applications, depending on a number of variables such as the radar cross section (RCS), the velocity, the range, the shape, and other characteristics of the target, and even the weather conditions and the characteristics and amount of clutter, detection of the target can be optimized by controlling parameters such as the PRF, the duty cycle of the pulses, the wavelength λ of the radio signal, and the direction and shape of the beam.
Also known to those skilled in the art, electronic beam steering and beam forming are enabled with agile beam radars that utilize a single antenna capable of changing the direction and/or shape of the beam to scan across multiple directions, for example, by utilizing a phased array antenna.
In the field of data communications, time division multiplexing (TDM) is a process known to those skilled in the art in which two or more apparently simultaneous channels are derived from a given frequency spectrum, i.e., bit stream, by interleaving pulses representing bits from different channels.
It is known to those skilled in the art that radar systems are frequently used to perform multiple ones of these functions. The most common conventional radar systems capable of performing multiple functions perform those functions sequentially. Moreover, many conventional systems suffer from slow agile beam updates and slow receiver or exciter frequency switching. Further, conventional systems frequently lack programmable waveforms and timing control.
For example, in a system performing SAR imaging, it may take 40 seconds to obtain an image. If such a system is instructed to sequence through multiple functions, the resources are tied up for the entire 40 seconds before the next sequential function may begin. During this time, a missile could be launched, presenting a serious problem for a pilot.
A multi-functional agile beam pulse radar system that interleaves multiple radar signals to achieve essentially simultaneous operation of multiple functions has been disclosed in the patent issued to Wittenberg, U.S. Pat. No. 6,714,157. However, this document lacks a detailed discussion of the arrangement of particular modes or groups of modes for improving the operation and compatibility of the plural radar functions. Thus, there is a need in the art for an improved agile-beam system and method for concurrent operation of a plurality of radar modes.